Catalysts based on nickel as the active catalyst component for the hydrogenation of aldehydes are part of the prior art. For example, EP-A-322 049 describes a hydrogenation catalyst comprising
1) a molar ratio of SiO.sub.2 /Ni=0.15-0.35 PA1 2) a molar ratio of (Mg or Ba)/Ni=0-0.15, PA1 25% to 50% by weight of (metallic) nickel PA1 10% to 35% by weight of nickel oxide PA1 4% to 12% by weight of magnesium oxide PA1 1% to 5% by weight of sodium oxide PA1 The reminder is support material. PA1 a) 5 to 10 atomic layers on the surface of the hydrogenation catalyst contain, as determined by SAM analysis, 18 to 30, preferably 20 to 28, atom % Ni, 1.2 to 3.0, preferably .5 to 2.5, atom % Na, and 2.8 to 4.8, preferably 3.2 to 4.5, atom % Mg; PA1 b) the metallic nickel surface area is, as determined by chemisorption of hydrogen, 100 to 130 m.sup.2/ g Ni; PA1 c) the catalyst contains aluminium oxide or silicon dioxide, particularly in the form of silicic acid, silica gel, kieselguhr, or siliceous earth, as the support material.
in which part of the nickel is present in metallic form.
The known hydrogenation catalysts based on nickel can be used in the hydrogenation of aldehydes only at temperatures up to about 100.degree. C., since increasing the hydrogenation temperature leads to the formation of undesired by-products which can sometimes only be removed by complicated distillation.